EnumSwitchStatementWhichMissesCasesInspection: utilize possible values list

plugins/InspectionGadgets/src/com/siyeh/ig/controlflow/EnumSwitchStatementWhichMissesCasesInspection.java

@@ -120,12 +120,17 @@ public class EnumSwitchStatementWhichMissesCasesInspection extends AbstractBaseJ
         if (constants.isEmpty()) return;
         CommonDataflow.DataflowResult dataflow = CommonDataflow.getDataflowResult(expression);
         if (dataflow != null) {
-          Set<Object> values = dataflow.getValuesNotEqualToExpression(expression);
-          for (Object value : values) {
+          Set<Object> notValues = dataflow.getValuesNotEqualToExpression(expression);
+          for (Object value : notValues) {
             if (value instanceof PsiEnumConstant) {
               constants.remove(((PsiEnumConstant)value).getName());
             }
           }
+          Set<String> values = StreamEx.of(dataflow.getExpressionValues(expression)).select(PsiEnumConstant.class)
+            .map(PsiEnumConstant::getName).toSet();
+          if (!values.isEmpty()) {
+            constants.retainAll(values);
+          }
         }
         if (constants.isEmpty()) return;
         String message = buildErrorString(aClass.getQualifiedName(), constants);

plugins/InspectionGadgets/testsrc/com/siyeh/ig/controlflow/EnumSwitchStatementWhichMissesCasesInspectionTest.java

@@ -24,6 +24,7 @@ import org.jetbrains.annotations.Nullable;
 /**
  * @author Bas Leijdekkers
  */
+@SuppressWarnings("EnumSwitchStatementWhichMissesCases")
 public class EnumSwitchStatementWhichMissesCasesInspectionTest extends LightInspectionTestCase {
 
   public void testSimple() {
@@ -120,7 +121,36 @@ public class EnumSwitchStatementWhichMissesCasesInspectionTest extends LightInsp
            "  }\n" +
            "}");
   }
-  
+
+  public void testDfaPossibleValues() {
+    doTest("enum E {A, B, C}\n" +
+           "\n" +
+           "class X {\n" +
+           "  void m(E e) {\n" +
+           "    if(e == E.A || e == E.B) {\n" +
+           "      switch (e) {\n" +
+           "        case A:\n" +
+           "        case B:\n" +
+           "      }\n" +
+           "    }\n" +
+           "  }\n" +
+           "}");
+  }
+
+  public void testDfaPossibleValuesNotCovered() {
+    doTest("enum E {A, B, C}\n" +
+           "\n" +
+           "class X {\n" +
+           "  void m(E e) {\n" +
+           "    if(e == E.A || e == E.B) {\n" +
+           "      /*'switch' statement on enum type 'E' misses case 'B'*/switch/**/ (e) {\n" +
+           "        case A:\n" +
+           "      }\n" +
+           "    }\n" +
+           "  }\n" +
+           "}");
+  }
+
   public void testJava12Preview() {
     doTest("enum E {A, B, C}\n" +
            "\n" +